An exemplary case report of a patient who developed an unpredictable sudden, late-onset clozapine-related life-threatening agranulocytosis expressed by a nadir of 14 polymorphonuclear cells/microL, and subsequently underwent protective hospitalisation and broad spectrum, empiric antimicrobial therapy and also experienced serious intolerance to a number of administered antibiotic and antifungal agents, is reported and discussed on the grounds of the available evidence from the literature.